Association Between Computed-Tomography-Derived Erector Spinae Muscle Characteristics and Swallowing Outcomes in Older Patients with Pneumonia

Background/Objectives: Trunk muscle mass and quality may be related to swallowing function; however, it is unclear whether the same trend is observed in older patients with pneumonia. We aimed to determine the impact of the mass and quality of the erector spinae muscles (ESM), measured using chest computed tomography (CT), on swallowing function decline during hospitalization. Methods: The participants were patients hospitalized at Sanuki Municipal Hospital with a diagnosis of pneumonia who underwent pulmonary rehabilitation (PR). A total of 450 patients met the eligibility criteria and were included in the analysis. The cross-sectional area of the ESM normalized by body surface area (ESMCSA/BSA) was measured from chest CT images as an indicator of muscle mass, whereas the CT attenuation value of the ESM (ESMCT) was used as an indicator of muscle quality. The primary outcome was the Functional Oral Intake Scale (FOIS) score at discharge. Results: Patients with a FOIS score of 6–7 at discharge exhibited significantly higher ESMCSA/BSA values than those with lower FOIS scores. In ordinal logistic regression analysis, ESMCSA/BSA was independently associated with the FOIS score at discharge (odds ratio, 1.09; 95% confidence interval, 1.03–1.15; p = 0.004). However, this association was no longer significant after adjustment for the Functional Independence Measure score at the start of PR. In contrast, ESMCT, an indicator of muscle quality, was not associated with FOIS score at discharge. Conclusions: In older patients with pneumonia, ESM may reflect overall physical function, which should be considered when interpreting its association with swallowing outcomes.